(Reuters)--Police in Sagamihara City were reportedly interrogating a man on Tuesday (July 25th) suspected of killing at least 19 disabled people in what some are calling Japan's biggest mass murder.

Police arrested Satoshi Uematsu, 26, a former employee at the facility located in Sagamihara City in Kanagawa Prefecture, about 25 miles (40 km) southwest of Tokyo, after he turned himself in.

At least one media report said Uematsu had called for severely disabled people to be euthanised.

A vehicle in the police station parking lot, reportedly belonging to the suspect, was covered in a blue plastic sheet.

Earlier footage on local Japanese television stations showed the car spattered with blood stains.

Staff called police at 2.30 a.m. local time (1730 GMT Monday) with reports of a man armed with a knife on the grounds of the Tsukui Yamayuri-En facility, media reported.

The 3-hectare (7.6 acre) facility, established by the local government and nestled on the wooded bank of the Sagami River, cares for people with a wide range of disabilities, local media sais, quoting an unidentified employee.

Police recovered a bag with several knives, at least one stained with blood, the Kanagawa prefecture official said.